N The Channel 国家重点实验室 Let w:be a binary-input discrete-memoryless channel X W >Input alphabet:=0,1 >Transition probabilities:W(ylx),x∈X,y∈y o Two independent uses of the channel W xi>w →Y xw→g Nindependent copies of W:WN:XN->YN w')=IIwG,I) 5 The Channel Let be a binary-input discrete-memoryless channel  Input alphabet:  Transition probabilities: , , Two independent uses of the channel W N independent copies of W: 5 X1 Y1 X2 Y2 W W W :  →  ={0,1} Wyx ( ) | x∈ y ∈ : NN N WX Y → 1 1 1 ( | ) (|) N N N N i i i W y x Wy x = =∏